Dear Gary,
ASDF will always *try* to upgrade itself before every operation. That's the only way to prevent a catastrophic upgrade mid-operation.
If you want it not to upgrade itself, simple: don't include it in your source-registry, central-registry, etc.
Also, ASDF will refuse to "upgrade" itself to an older version, so to override an asdf.asd in your source-registry, you can put an artificial empty asdf.asd higher up in there, without a version.lisp-expr in there, so ASDF will refuse to upgrade from it.
—♯ƒ • François-René ÐVB Rideau •Reflection&Cybernethics• http://fare.tunes.org Individualism is thus an attitude of humility before this social process and of tolerance to other opinions, and is the exact opposite of that intellectual hubris which is at the root of the demand for comprehensive direction of the social process. — Friedrich August Hayek, The Road to Serfdom